Telephone system



June 15, 1937.

w. PFAFF TELEPHONE SYSTEM Filed June 14, 1955 1N VENTOR. WALTER PFAFF %w ATTORNEY.

Patented June 15, 1937 UNITED STATES T OFFIQE TELEPHONE SYSTEM Walter Pfafi, Berlin,

Germany, assignor to Application June 14, 1935, Serial No. 26,558 In Germany June 22, 1934 6 Claims.

This invention relates in general to an arrangement employing double operating switches in an automatic telephone system in which when the switch is used as a final selector an impulsing arrangement is connected up for the purpose of setting. further numerical impulse switches which are accessible over the double operating switch.

More particularly the present invention consists in switching means that are associated with the double operating switch which, dependent upon the side of the trunk from which the seizing impulse is received and also the selected traffic direction, connects up switching devices for the transmission of trains of impulses over the selector.

The drawing shows one embodiment of the invention. It represents a private installation in which local connections between the subscribers NI and N2 are set up in known manner over the call finder AS and the final selector LW. If the local subscriber NI desires an exchange connection, then when he removes his receiver the call finder AS is set on to the line of the calling subscriber NI in known manner. After this setting the subscriber is guarded by the short circuiting of winding II of relay C over contact Ic. For the purpose of setting up an exchange connection the final selector LW is set on to a particular contact over which relay A12 is energized. Relay An completes the following circuit for relay R: contacts 20m, 3s, relay R, Relay R closes a circuit for the rotary magnet DAW over relay interrupter RU, contacts Sol, 61", winding II of relay E, rotary magnet DAW, The rotary magnet DAW is operated by the relay interrupter RU until the following circuit, prepared by the opening of contact Ir and the closing of contact 81, is completed over wiper d of the exchange selector AW: winding III of relay CI, contact 31', wiper d of exchange selector AW, lead 9, wiper d of the call finder, relay PI, wiper d of the final selector, resistance W, Relay CI operates in this circuit and by opening the circuit of magnet DAW at contact 5cI brings the switch to rest. In the test circuit over Wiper d of the exchange selector AW, relay PI in the final selector LW also operates. Relay PI in known manner which is not shown initiates the release of the final selector LW and the freeing oi the call finder AS, whereupon relay C is released and removes the guarding at contact la. The following circuit can now become effective over wiper c of the exchange selector AW: contact IIicI, winding Iof relay CI, relay Pa, wiper c of exchange selector AW, lead I I, relay T, Relay CI effects switching through at contacts IZcI and I 30! so that the following feed circuit is now completed for the subscriber NI: winding I of relay S, winding I of relay X, contact I2cI, wiper a, lead I4, over loop of the calling subscriber NI, lead I5, wiper b of exchange selector AW, contact I 3cl, winding II of relay X, winding II of relay S, Only relay S operates in this circuit since relay X is a difierential relay. By means of relay S the start circuit for relay R is interrupted at contact 38. The calling subscriber is now connected to the exchange line AL. The impulse transmitted by the subscriber 15 NI are received by relay S and repeated to the exchange line AL at contact I68.

Establishment of an incoming exchange connection If an exchange call arrives over the exchange line AL relay A is energized by ringing current, and over: lamp L, contacts Ilas, I8a, connects up the lamp L. Relay H is also energized over: relay H, contact I8a, so that the following holding circuit is completed for the lamp L: lamp L, contact I'Ias, I9h, 20c, ZIoI, Relay H locks up over: relay H, contacts I9h, 20c, ZIoI, By the lighting of the lamp L the operator is notified of the incoming exchange call and therefore operates her speaking key momentarily after she has operated the switchhook HU. By the opening of contact 2411b and the closing of contact 2211b of the speaking key the following circuit is completed for relay AS: switchhook I-IU, contact 2201) of the speaking key, relay As, Over contact 23118 the following locking circuit is completed for relay AS after the speaking key has been restored to normal: switchhook HU, contacts 2411b, 2311s, relay AS, Relay AS at contact I ias interrupts the circuit for the lamp L. Over: contacts 451ml, 46ers, Ir, wiper d of exchange selectors, in position 0, winding I of relay E, relay E is energized and by opening its contact 26c interrupts the locking circuit for relay H so that relay H restores its contacts to normal. Relay AS opens contacts 2511s and 2611s and closes contacts 21:13 and 23as so that the operators speaking set BA is connected to the calling exchange line AL and she can therefore ascertain the wishes of the calling exchange subscriber. In order to extend the exchange call to the desired local station the operator presses the connecting key whereupon relay VS is energized over contact 28v. Relay VS closes a locking circuit for itself over: switchhook HU, contacts 24ab, 3808, relay VS, relay VS also energizes relay ASI over: switchhook HU, contacts ch, 3003, 3los, 32as, winding I of relay ASI, By the opening of contacts 330s and 3411s and the closing of contacts 350s and 3612s the operators speaking set is transferred from the exchange line AL tothe line 31/38. By the closing of contacts 39ml and 40asl the line 31/38 is connected with the wipers of the exchange selector AW of the calling exchange line AL. Relay ASI at contact 4511s! opens the circuit for relay E. By the transfer of the exchange line AL to the line 37/38 relay J is energized over: winding II of relay J, contact 38123, loop of the operators speaking set BA, contact 3508, winding I of relay J, The operator now manipulates her dial in her set whereupon relay J is energized corresponding to the transmitted digit. Relay J repeats the impulses to the rotary magnet DAW in the following circuit: switchhook HU, contacts My, 4208, 43as, M'cl, winding II of relay E, rotary magnet DAW, During the impulses train relay E remains energized. At the end of the im ulse train and the consequent release of relay E, the following test circuit is completed: contacts 41h, 48c, windings II and I of relay Cl, relay P2, wiper c of switch AW, lead H, relay T, Relay P2 is not energized in this circuit. Relay Cl operates, however, and guards the called subscriber by short-circuiting winding II of relay Cl over contact Incl; Relay Cl switches the exchange line through at contacts 120i and [301. The subscriber Ni is now rung in known manner which is not shown. When the subscriber replies, relay S operates and switches the exchange line through at contact lGs. The operator now. replaces her receiver and thereupon opens the circuits for relays VS, AS, and-ASL whereupon these relays restore to normal; The exchange line is switched through at contacts as, and 26as and the exchange subscriber is now connected with the desired local subscriber.

Extension of an incoming exchange call over a trunk Zine leading to a further exchange If an. exchange call arrives and the calling exchange subscriber desires tospeak to a subscriber of another exchange accessible over a trunk line VL, it is necessary that the exchange selector AW shall be set on to the trunk line VL. The setting of the switch takes placein the manner already described for incoming calls. After the setting, however, relay P2- is energized aswell as relay Cl, and relay P2 closes the following circuit for relay D: relay D, contacts 49722, 581181, Relay D- at contacts 5Id completes an impulse bridge across the line 31/38 so that further impulses transmitted by the operator are repeated by dial contact 5U over the exchange selector to the trunk line VL and hence to'the connecting devices connected to the trunk line. These trains of impulses cannot affect the rotary magnet DAW since relay Cl is energized in the test circuit of the exchange selector and hence the circuit for the rotary magnet DAW is opened at contact Mel. The relay S cannot be influenced by the trains of impulses transmitted over the speaking leads by meansof contact 52 7' since relay P2 has short circuited winding I of relay S over contact 53112 and relay S is slow torelease, and hence cannot be operated during the interruptions at contact 529'. Since during the setting over the trunk line VL relay ASI remains energized independent of the operation of the key Vi, the following circuit is completed by the relay P2 for the relay ASI: switchhook HU, contacts 24gb, 23d8, 54102, winding II of relay ASI, Relay ASI therefore remains energized until the operator restores the switchhook to normal by replacing the handset.

It is therefore seen that devices are provided, particularly relay D, which dependent upon the side of the trunk from which the seizing impulse is received (in the case of incoming connections from the exchange relay ASI is energized), and the selected traffic direction (setting of the exchange selectcr on to the trunk line to cause the energization of relay P2) connect up switching devices (impulse contact 527') for the transmission of impulses over the selector.

Having described the invention, what is considered to be new and is desired to be protected by Letters Patent will be set forth in the following claims.

What is claimed is:

1. In a telephone system, a sub-exchange, a trunk line extending from a distant exchange connected to said sub-exchange, a selector switch in which said trunk line terminates, wipers on said selector switch having access to the subscribers lines in said sub-exchange, a second trunk line extending to another exchange accessible to said selector switch wipers, means operated responsive to an outgoing trunk call to the distant exchange from a subscribers line in the sub-exchange for operating said selector wipers as a finder to find the calling line and connect it with the first trunk line, an opera'- tors position for receiving incoming trunk calls from the distant exchange over said first trunk first trunk line with said second trunk line and.

extend the said other incoming trunk call to the other exchange.

2. In a telephone system, a sub-exchange, subscribers lines therein, a two-way trunk line ex-v tending from a distant exchange connected to said sub-exchange, a second trunk line extending to another exchange, a selector switch connected to said two-way trunk line, wipers on said switch having access to said subscribers lines and to said second trunk line, means responsive to an outgoing trunk call to the distant exchange from a .subscribers line for operating said selector switch as a finder to connect the calling line with said two-way trunk line by way of said wipers, an operators position connected to said two-way trunk line, means controlled by saidoperator'in answering an incoming trunk call from the. distant exchange over said two-way trunk line for a subscriber for operating said selector switch to connect a subscriber with said two-way trunk by way of said wipers to complete the incomingtrunk call from the distant exchange,- and means controlled by the operator in case the incoming trunk call is for the other exchange for operating said selector switch to connect with said second trunk line and extend the last incoming trunk call thereto over said wipers;

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3. In a telephone system as claimed in claim 2, including impulse sending means at said operators position, and means responsive to the connection of said two-way trunk line with said second trunk line for automatically connecting said impulse sending means to said two-way trunk line.

4. In a telephone system as claimed in claim 2, including impulse sending means at said operators position, means in said selector switch for automatically connecting said impulse sending means to said two-way trunk line in case a call is extended from said two-way trunk line to the second trunk line extending to the other exchange, said impulse sending means prevented from being connected to said two-way trunk line in case the selector switch is used as a finder to extend a call from a subscriber's line to the two-way trunk line.

5. In a telephone system, a sub-exchange having subscribers lines therein, a selector switch, a two-way trunk line connected to said selector switch, a second trunk line connected to another exchange, means responsive to a call from a subscribers line for operating said selector switch as a, finder to connect the calling line with the said two-way trunk line, an operator's position connected to said two-way trunk line, means controlled by said operator for operating said selector switch to connect an incoming call over said two-way trunk line with a called subscribers line, means controlled by said operator for operating said selector switch to connect a call from said two-way trunk line to said second trunk line leading to said other exchange, and switching means in the selector switch depending upon the type of call made for controlling the operation of said selector switch to connect with the desired traific direction.

6. In a telephone system as claimed in claim 5, impulse sending means connected in said twoway trunk line to repeat impulses to said second trunk line, impulse repeating means in said twoway trunk line for repeating impulses in a call from a subscriber's line to said two-Way trunk line, and means controlled by the operation of said switching means for preventing the operation of said impulse repeating means when the call is extended from the two-way trunk line to said second trunk line.

WALTER PFAFF. 

